The present invention relates to apparatus for cleaning the submerged surface of a swimming pool; and more particularly, it relates to an automatic pool cleaner of the water interruption type.
In a water interruption pool cleaner, water flow through the head of the device is created by suction applied to an outlet connected by a flexible hose to the swimming pool water circulation system. An automatic valve member in the head interrupts the water flow and simultaneously reduces suction adherence to the submerged surface. The sudden interruption of water flow produces a change in momentum of the mass of water in the device and, through the fundamental action/reaction principle, creates a motive force on the device. Illustrative of water interruption type pool cleaners are those described in the prior art patents of: U.S. Pat. No. 3,803,658 (Raubenheimer); U.S. Pat. No. 4,023,227 (Chauvier); U.S. Pat. No. 4,208,752 (Hofmann); and of application Ser. No. 749,793 filed June 28, 1985 and titled "Valve Assembly." Further illustrative of wate interruption type pool cleaners are the BARACUDA ALPHA pool cleaner and the KREEPY KRAULY pool cleaner.
Water interruption pool cleaners include a head having an open mouth inlet to admit water. Water is sucked through the head by suction applied to an outlet provided for connection to a flexible hose. The water flow passage between the inlet and the outlet is inclined at an angle. The head, however, is configured to have the open mouth lie in a substantially horizontal plane to facilitate cleaning planar, submerged surfaces. Accordingly, the water flow path through the head from the open mouth to the outlet is disposed at an angle with respect to the planar surface to the cleaned.
The motive force imparted to the head of the device upon an interruption of water flow is along a line of action following the direction of water flow. The net motive force includes a component parallel to the plane of the submerged surface and in the direction of the hose connection. Thus, forward movement in normal operation is in the direction of the outlet and connected flexible hose. This movement presents a problem when the device encounters an obstruction such as, for example, steps in the pool, a pool ladder on a wall, or a bench formed in a pool wall, in that the device becomes lodged between such obstructions and the pool wall. Further, in pools having substantially right angle corners, the device can become lodged in a corner and cannot extricate itself.
Heretofore, the problem of a water interruption pool cleaner becoming lodged and unmovable by reason of an obstruction in the pool has been addressed by various bumper guard structures affixed to the device. Illustrative of such bumper guards is that shown in U.S. Pat. No. 4,463,468. While helpful, bumper guards are not wholly satisfactory. The bumper guards are themselves prone to lodging and entangling with obstructions. Also, deflection of the device away from obstructions can lead to certain areas of the pool remaining uncleaned. Accordingly, there continues a need for a solution to the problem.